This invention relates to a novel crosslinkable resin composition and a novel method for producing a laminate using said composition. More specifically, the novel resin composition of this invention has improved heat resistance, strength and adhesion while retaining the superior electrical properties of crosslinked polyethylene resin.
Crosslinked polyethylene has greatly improved heat resistance and durability over non-crosslinked polyethylene. For example, radiation-crosslinked polyethylene is used as a cable coating for submarine cables, and organic peroxide-crosslinked polyethylene is used, for example, in foamed products. Investigations are also being made to use crosslinked polyethylene commercially as a resin for printed circuit boards by utilizing its electrical properties.
As can be anticipated from its molecular structure, however, the crosslinked polyethylene has insufficient flexural strength even when it is combined with a substrate. It has a glass transition temperature, measured by the torsional vibration method, of about 50.degree. C., and a flexural strength, at a high temperature of, say, 100.degree. C., of as low as about 400 kg/cm.sup.2. When it is used in a copper-clad laminate, the adhesion of a copper foil to it is sufficient.
According to this invention, the above disadvantages are overcome by a novel method of blending a specified thermosetting resin composition with the crosslinked polyethylene. The crosslinkable resin composition of this invention has a high glass transition temperature measured by the torsional vibration method and a good flexural strength at high temperatures, and is useful as films, molded articles, laminates, etc.